In many of the known ship propulsion systems having controllable pitch propellers, separate controls are required for engine speed and propeller pitch, respectively. This can be an exhausting job for the operator since all the variable conditions encountered due to ship load, water currents, waves, wind, etc. have an effect on the engine loading. It would be desirable, therefore, to coordinate propeller pitch and engine speed in such a manner as to prevent overload of the engine by adjusting the pitch of the propeller automatically according to prevailing engine load.